PCNE Configuring Network Services Practice Question
Exhibit
Refer to the exhibit.
```
$ gcloud compute routers describe my-router --region us-central1
creationTimestamp: '2023-01-15T10:00:00.000-08:00'
description: Router for on-prem connectivity
id: '1234567890123456789'
kind: compute#router
name: my-router
network: https://www.googleapis.com/compute/v1/projects/my-project/global/networks/default
region: https://www.googleapis.com/compute/v1/projects/my-project/regions/us-central1
bgp:
asn: 65001
advertiseMode: CUSTOM
advertisedGroups:
- ALL_SUBNETS
advertisedIpRanges:
- range: 10.0.1.0/24
description: On-prem subnet
keepaliveInterval: 20
```You have a Cloud Router with the configuration shown. The on-premises network (ASN 65002) is not receiving any routes from Google Cloud. What is the most likely cause?
⚠ Common exam trap
Google Cloud often tests the misconception that a BGP session being 'Established' guarantees route exchange, but in Google Cloud's custom advertise mode, the session can be up while no routes are advertised due to missing custom advertisement configuration.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The router is in custom advertise mode but does not advertise the VPC subnets
When a Cloud Router is configured in custom advertise mode, it only advertises the routes explicitly specified in the custom advertisement list. If the VPC subnets are not included in that list, the on-premises network will not receive any routes from Google Cloud, even if the BGP session is established. This is the most likely cause because the question states the on-premises network is not receiving any routes, which aligns with a missing custom advertisement rather than a session or timer issue.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The BGP keepalive interval is set too low
Why it's wrong here
20 seconds is standard.
- ✗
The BGP session is not established
Why it's wrong here
Session might be up but no routes because of custom mode.
- ✓
The router is in custom advertise mode but does not advertise the VPC subnets
Why this is correct
Custom mode overrides default; must explicitly advertise VPC subnets.
- ✗
The on-premises subnet 10.0.1.0/24 is not advertised
Why it's wrong here
It is advertised in custom mode.
Visual reference
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCNE practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCNE exam.